CN115672326A

CN115672326A - Preparation method and application of environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material

Info

Publication number: CN115672326A
Application number: CN202211222065.1A
Authority: CN
Inventors: 王一平; 李陈; 雷晓东; 闫冰
Original assignee: Beijing University of Chemical Technology
Current assignee: Beijing University of Chemical Technology
Priority date: 2022-10-08
Filing date: 2022-10-08
Publication date: 2023-02-03

Abstract

The invention provides a preparation method and application of an environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material. The environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material is prepared by a one-step coprecipitation method. Mixing a divalent metal (calcium or magnesium) salt solution and a trivalent metal (aluminum or aluminum and iron) salt solution to be marked as a solution A; recording an alkali solution (sodium hydroxide or potassium hydroxide) with a certain concentration as a solution B; simultaneously dripping the solution A and the solution B into persulfate solution; and after aging, washing and freeze-drying the precipitate to obtain a solid sample, namely the environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material. When the prepared material is used for treating organic wastewater containing new antibiotic pollutants, the material has a remarkable treatment effect.

Description

Preparation method and application of environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material

The technical field is as follows:

the invention relates to application of an advanced oxidation technology in the field of environmental remediation, in particular to a preparation method and application of an environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material.

Background art:

the quinolone antibiotics are important synthetic antibiotics and are widely applied to treatment of bacterial diseases and prevention of livestock aquaculture. However, since quinolone antibiotics are chemically stable and difficult to biodegrade, they cannot be effectively removed by conventional techniques, thereby releasing them into water and soil environments. Research shows that antibiotics in the environment can accelerate the evolution of bacterial drug resistance, and finally pose a threat to public health and safety. Therefore, new technologies capable of remarkably dealing with the remaining quinolone antibiotics in the environment are urgently needed.

In recent years, persulfate advanced oxidation has attracted much attention in the treatment of refractory organic pollutants. In general, persulfate can be activated by heating, ultraviolet irradiation, ultrasonic waves, alkali solution, transition metal ions, heterogeneous catalysts, and the like, and oxidative degradation of organic pollutants is achieved by generating active oxygen species such as sulfate radicals, hydroxyl radicals, superoxide radicals, and singlet oxygen, or electron transfer. Heterogeneous activated persulfates are considered the best method of activation because the catalyst is simple to use, reusable, and does not introduce additional energy or toxic chemicals into the reaction system.

Layered Double Hydroxides (LDHs) are anionic layered materials and are assembled by intercalation of metal hydroxides and interlayer anions, and are commonly called hydrotalcite-like compounds. The chemical composition is usually [ M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^x+ (A ^n- ) _x/n ·zH ₂ O, wherein M ²⁺ And M ³⁺ Are respectively divalent and trivalent cations, A ^n- Is an interlayer anion. The hydrotalcite-like material has rich surface hydroxyl groups, the composition and proportion of the metal elements of the laminate can be adjusted, and the types of interlayer anions can be adjusted. Moreover, the method for synthesizing the hydrotalcite-like material is simple, the raw materials are easy to obtain, and the cost is low. The advantages lay a good foundation for the heterogeneous phase activated persulfate material to be used for removing new antibiotic pollutants.

Chinese patent CN110479278A discloses a method for preparing two-dimensional cobalt-aluminum composite oxide by using hydrotalcite and its application. The method for preparing the two-dimensional cobalt-aluminum composite oxide by using the hydrotalcite comprises the following steps: mixing a cobalt salt solution, an aluminum salt solution, a hexamethylenetetramine solution and a nitrogen-rich compound solution to form a mixed solution, carrying out hydrothermal reaction, and separating out a solid product to obtain intercalated hydrotalcite; roasting the intercalated hydrotalcite at high temperature, and cooling to obtain multilayer hydrotalcite; putting the material into an organic solvent for ultrasonic treatment, and then separating solid matters out to obtain single-layer hydrotalcite; and roasting the single-layer hydrotalcite at high temperature to obtain the two-dimensional cobalt-aluminum composite oxide. When the material is used for catalytically activating persulfate to degrade aniline wastewater, the degradation rate of p-aniline is improved.

Chinese patent CN112044367A discloses a cobalt-manganese hydrotalcite aerogel and a preparation method and application thereof. Adding cobalt nitrate and manganese nitrate solution into water to form a salt solution, and then mixing the salt solution with an alkali solution to obtain a precipitate CoMn-LDH; and mixing CoMn-LDH and a graphene oxide solution, performing ultrasonic dispersion, adding sodium ascorbate, performing heating reaction on the mixed solution, and performing freeze drying to obtain the cobalt-manganese hydrotalcite aerogel. Under the excitation of visible light, the hole-electron pair of the cobalt-manganese hydrotalcite accelerates the separation, and the excellent conductivity and wide electron transfer channel of the three-dimensional aerogel accelerate the conduction of electrons, so that persulfate is promoted to generate more sulfate radicals, hydroxyl radicals and other active oxidants to oxidize and decompose organic pollutants, and finally water and carbon dioxide are generated.

Chinese patent CN110270364A discloses a preparation method and application of a supported graphite phase carbon nitride composite material. The invention adopts a two-step method to synthesize the layered nickel-iron hydrotalcite loaded graphite-phase carbon nitride composite material, firstly grinding a certain amount of urea into powder, synthesizing porous graphite-phase carbon nitride through high-temperature condensation treatment, and then repeatedly washing by using absolute ethyl alcohol and deionized water to load the layered nickel-iron hydrotalcite into a matrix and a pore channel of the porous graphite-phase carbon nitride. The catalyst shows stable and excellent catalytic activity in the oxidative degradation of methylene blue by activating persulfate.

The technology has certain effects on the activation of persulfate and the treatment of organic pollutants in water. However, most of the chemicals used for preparing the hydrotalcite-like material are heavy metal salts, and the sulfate as a byproduct after the persulfate activation remains in the water environment, so that the concentration of the sulfate is too high, and secondary pollution is caused.

The invention aims to provide a preparation method and application of an environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material, wherein metal elements of a material laminated plate are calcium, magnesium, aluminum and iron elements which are harmless to the environment, persulfate is inserted into the interlayer of the hydrotalcite-like compound through a hydrotalcite-like structural laminated plate so as to control the release of byproducts after persulfate activation, and quinolone antibiotics such as ciprofloxacin, oxyfloxacin and the like in water are efficiently removed. The invention provides a scheme for the design and application of the catalytic material of the advanced oxidation technology.

The invention content is as follows:

1. a preparation method of an environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material is characterized by comprising the following steps: uniformly mixing a divalent metal nitrate solution and a trivalent metal nitrate solution to be recorded as a solution A; taking the alkali solution as solution B; adding the solution A and the solution B into a persulfate solution which is introduced with nitrogen at the same time in a room temperature environment, and keeping the pH value of the solution at 9-12; after the dropwise addition is finished, the reaction mixed solution is aged for 10 to 20 hours in the nitrogen atmosphere; then centrifugally separating, washing the obtained sample to be neutral, and freeze-drying; the finally obtained solid sample is the environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material;

wherein, the divalent metal salt in the divalent metal nitrate solution is a mixed solution of calcium nitrate and magnesium nitrate, and the ratio of calcium nitrate: the molar ratio of the magnesium nitrate is 0-1; the trivalent metal salt in the trivalent metal nitrate solution is a mixed solution of ferric nitrate and aluminum nitrate, wherein the ratio of ferric nitrate: the molar ratio of the aluminum nitrate is 0-1; divalent metal nitrate solution: the molar ratio of the trivalent metal nitrate solution is 2-4;

adding a divalent metal nitrate and a trivalent metal salt with twice molar weight into an aqueous alkali solution of sodium hydroxide or potassium hydroxide, wherein the aqueous alkali solution is the solution of sodium hydroxide or potassium hydroxide;

the persulfate solution is potassium persulfate or sodium persulfate solution, and the molar weight of the persulfate solution is twice that of the trivalent metal salt solution.

2. The use of the slow-release catalytic material prepared by the preparation method of claim 1 in water treatment is characterized in that:

the prepared slow-release catalytic material is added into 10 mg/L quinolone antibiotic organic wastewater, and under the stirring condition, after 120 minutes, the removal rate of the quinolone antibiotic in the water reaches more than 95%; the quinolone antibiotic is one of ciprofloxacin, ofloxacin, enrofloxacin and norfloxacin.

The beneficial effects of the technology of the invention are as follows:

according to the invention, the sustained-release catalytic material of persulfate intercalation is prepared by adopting calcium, magnesium, aluminum and ferric salt, and the metal salts used in the formula are all metals harmless to the environment, so that the pollution risk to the environment is avoided; meanwhile, the prepared material can fix the sulfate as a byproduct after the persulfate is activated between layers, so that the release of the sulfate to a water environment is effectively reduced. The preparation method of the material is one-step synthesis, and compared with the two-step synthesis of an ion exchange method, the preparation method provided by the invention is simpler to operate and mild in preparation conditions. The material has excellent degradation performance, and can quickly remove quinolone antibiotics.

Drawings

FIG. 1 is a material synthesis scheme

FIG. 2 is a graph of ciprofloxacin degradation performance of example 1

FIG. 3 is a graph of ciprofloxacin degradation performance of example 2

FIG. 4 is a graph of the ciprofloxacin degradation performance of example 3

FIG. 5 is an X-ray diffraction chart of the synthesized material of example 3 before and after use

FIG. 6 is a graph showing the degradation performance of benzoic acid, nitrobenzene and furfuryl alcohol in example 4

FIG. 7 is electron paramagnetic resonance diagram for singlet oxygen capture

FIG. 8 is electron paramagnetic resonance plot for the capture of hydroxyl and sulfate radicals

FIG. 9 is a graph of the ability of the synthesized material to degrade different quinolone antibiotics

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the respective embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Example 1

In the embodiment, a nitrate solution with a magnesium/aluminum molar ratio of 3 is selected, an alkali solution is a sodium hydroxide solution, the adding amount of the sodium hydroxide solution is 2 times of the total molar amount of a magnesium salt and an aluminum salt, potassium persulfate is 2 times of the molar amount of the aluminum salt, the salt solution and the alkali solution are simultaneously added into the potassium persulfate solution in a dropwise manner, the pH value is kept at 11 +/-0.2 in the dropwise manner, after the salt solution and the alkali solution are added, aging is carried out for 20 hours, an obtained sample is washed to be neutral, and freeze drying is carried out, wherein a solid sample is an environment-friendly persulfate intercalation hydrotalcite-like slow-release catalytic material and is marked as PDS-MgAl-LDH. Ciprofloxacin is selected as a target organic pollutant, and the performance of the prepared material for catalyzing and degrading quinolone antibiotics is evaluated.

The experimental procedure was as follows:

(1) And synthesizing PDS-MgAl-LDH. The preparation process of the material is shown in the attached figure 1. Weighing 0.045 mol of magnesium nitrate and 0.015 mol of aluminum nitrate, mixing and dissolving in 45 ml of deionized water, and marking as a salt solution; weighing 0.12 mol of sodium hydroxide, dissolving in 45 ml of deionized water, and recording as an alkali solution; 0.03 moles of potassium persulfate was weighed and dissolved in 160 ml of deionized water. And (3) dropping the salt solution and the alkali solution into the potassium persulfate solution at the same time, wherein the pH value is kept at 11 +/-0.2 in the dropping process. After the dropwise addition, the mixture is aged for 20 hours at room temperature, centrifuged, and the precipitate is retained and washed for multiple times until the pH of the supernatant is neutral after centrifugation. And (3) freeze-drying the solid for 24 hours to obtain a sample, namely PDS-MgAl-LDH.

(2) And (3) performing a ciprofloxacin degradation experiment by using the PDS-MgAl-LDH. Stock ciprofloxacin at 100 mg/l was prepared. 20 ml of the stock solution was measured, 180 ml of deionized water was added, and 0.2 g of PDS-MgAl-LDH was weighed into the contaminant solution. Wherein the ciprofloxacin content of the pollutant solution is 10 mg per liter, and the PDS-MgAl-LDH material concentration is 1 g per liter. The performance of the material prepared in the embodiment 1 of the invention for catalyzing and degrading ciprofloxacin is shown in the attached figure 2.

Example 2

In the embodiment, a salt solution with a calcium/aluminum molar ratio of 3 is selected, an alkali solution is a sodium hydroxide solution, the adding amount of the sodium hydroxide solution is 2 times of the total molar amount of added calcium and aluminum, potassium persulfate is 2 times of the molar amount of added aluminum, the salt solution and the alkali solution are jointly dripped into a potassium persulfate solution, the pH value is kept at 11 +/-0.2 in the dripping process, after the dripping of the salt solution and the alkali solution is finished, the aging is carried out for 20 hours, an obtained sample is washed to be neutral, and the freeze drying is carried out, so that a solid sample is the environment-friendly persulfate slow-release catalytic material which is marked as PDS-CaAl-LDH. Ciprofloxacin is selected as a target organic pollutant, and the performance of the prepared material for catalyzing and degrading quinolone antibiotics is evaluated.

The experimental procedure was as follows:

(1) And synthesizing PDS-CaAl-LDH. The preparation process of the material is shown in the attached figure 1. Weighing 0.045 mol of calcium nitrate and 0.015 mol of aluminum nitrate, mixing and dissolving in 45 ml of deionized water, and marking as a salt solution; weighing 0.12 mol of sodium hydroxide, dissolving in 45 ml of deionized water, and recording as an alkali solution; 0.03 moles of potassium persulfate was weighed and dissolved in 160 ml of deionized water. And (3) dropping the salt solution and the alkali solution into the potassium persulfate solution together under the nitrogen atmosphere, wherein the pH value is kept at 11 +/-0.2 in the dropping process. After the dropwise addition, maintaining the nitrogen atmosphere, aging at room temperature for 20 hours, centrifuging, keeping the precipitate, and washing for multiple times until the pH of the supernatant is neutral after centrifuging. And (3) freeze-drying the solid for 24 hours to obtain a sample, namely PDS-CaAl-LDH.

(2) And (3) performing a ciprofloxacin degradation experiment by using the PDS-CaAl-LDH. Stock ciprofloxacin at 100 mg/l was prepared. 20 ml of the stock solution was measured, 180 ml of deionized water was added, and 0.2 g of PDS-CaAl-LDH was weighed into the contaminant solution. Wherein the ciprofloxacin content of the pollutant solution is 10 milligrams per liter, and the concentration of the PDS-CaAl-LDH material is 1 gram per liter. The performance of the material prepared in the embodiment 2 of the invention for degrading ciprofloxacin is shown in the attached figure 3.

Example 3

In the embodiment, a salt solution with a magnesium/aluminum/iron molar ratio of 3.8 is selected, wherein the alkali solution is a sodium hydroxide solution, the adding amount of the sodium hydroxide solution is 2 times of the total molar amount of magnesium, aluminum and iron, and potassium persulfate is 2 times of the total molar amount of aluminum and iron, the salt solution and the alkali solution are added into the potassium persulfate solution together in a dropwise manner, the pH value is kept at 11 +/-0.2 in the dropwise manner, after the dropwise addition of the salt solution and the alkali solution is finished, the solution is aged for 20 hours, the obtained sample is washed to be neutral, and the solution is freeze-dried, and the solid sample is the environment-friendly persulfate slow-release catalytic material which is marked as PDS-MgAlFe-LDH. Ciprofloxacin is selected as a target organic pollutant, and the performance of the prepared material for catalyzing and degrading quinolone antibiotics is evaluated.

The experimental procedure was as follows:

(1) Synthesizing PDS-MgAlFe-LDH. The preparation process of the material is shown in the attached figure 1. Weighing 0.045 mol of magnesium nitrate, 0.012 mol of aluminum nitrate and 0.003 mol of ferric nitrate, mixing and dissolving in 45 ml of deionized water, and marking as a salt solution; weighing 0.12 mol of sodium hydroxide, dissolving in 45 ml of deionized water, and recording as an alkali solution; 0.03 moles of potassium persulfate was weighed and dissolved in 160 ml of deionized water. And (3) under the nitrogen atmosphere, dropping the salt solution and the alkali solution into the potassium persulfate solution at the same time, and keeping the pH value to be 11 +/-0.2 in the dropping process. After the dropwise addition, keeping the nitrogen atmosphere, aging at room temperature for 20 hours, centrifuging, reserving the precipitate, and washing for multiple times until the pH value of the supernatant is neutral after centrifugation. And (3) freeze-drying the solid for 24 hours to obtain a sample, namely PDS-MgAlFe-LDH.

(2) And (3) a PDS-MgAlFe-LDH ciprofloxacin degradation experiment. Stock ciprofloxacin at 100 mg/l was prepared. 20 ml of this stock solution was measured, 180 ml of deionized water was added, and 0.2 g of PDS-MgAlFe-LDH was weighed into the contaminant solution. Wherein the ciprofloxacin content of the pollutant solution is 10 milligrams per liter, and the PDS-MgAlFe-LDH material concentration is 1 gram per liter. The degradation performance of the material prepared in example 3 of the present invention is shown in figure 4.

(3) X-ray diffraction is a commonly used characterization method for analyzing the crystal structure of a material. The sample used in step 2 was retained and subjected to X-ray diffraction characterization, the results of which are shown in fig. 5.

Example 4

This example was carried out with radical and non-radical probe experiments using the samples prepared in example 3. Benzoic acid is a probe compound for hydroxyl and sulfate radicals, nitrobenzene is a probe compound for hydroxyl radicals, and furfuryl alcohol is a probe compound for singlet oxygen.

Preparing a solution of benzoic acid, nitrobenzene and furfuryl alcohol with the concentration of 3 millimoles per liter. 200 ml of the three solutions are respectively measured and placed in 3 glass conical flask containers, and 0.2 g of PDS-MgAlFe-LDH is respectively weighed and added into the three containers. Wherein the concentration of the PDS-MgAlFe-LDH material is 1 gram per liter. The removal of benzoic acid, nitrobenzene, furfuryl alcohol solution is shown in figure 6.

Example 5

In this example, the sample prepared in example 3 was subjected to electron paramagnetic resonance testing to detect whether hydroxyl radicals, sulfate radicals, and singlet oxygen were generated during the reaction. An electron paramagnetic resonance spectrometer is an instrument capable of directly detecting active oxygen species, and adopts 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trapping agent for hydroxyl radicals and sulfate radicals and 2, 6-Tetramethylpiperidine (TEMP) as a spin trapping agent for singlet oxygen. Wherein, DMPO concentration is 88 millimoles per liter, TEMP concentration is 20 millimoles per liter.

The specific detection process is as follows: to 200 ml of 10 mg/l ciprofloxacin solution was added 0.2 g of the sample prepared in example 3, 1 ml of the solution was aspirated at 0 minute, 5 minutes, and 10 minutes, respectively, and filtered with a 0.22 μm filter, and 0.5 ml of the filtered solution was mixed with 0.5 ml of a spin trap, shaken, and subjected to electron paramagnetic resonance testing. The test results are shown in fig. 7 and 8.

Example 6

In this example, the samples prepared in example 3 were used for degradation of ciprofloxacin, ofloxacin, enrofloxacin and norfloxacin, respectively.

200 ml of 10 mg/l ciprofloxacin, ofloxacin, enrofloxacin and norfloxacin solutions are respectively weighed, and 0.2 g of PDS-MgAlFe-LDH is respectively weighed and added into each pollutant solution. Wherein the concentration of the PDS-MgAlFe-LDH material is 1 gram per liter. The degradation performance of the slow-release catalytic material on four quinolone antibiotics in the example is shown in figure 9.

Effects of the embodiment

The persulfate intercalated hydrotalcite slow-release catalytic materials prepared in the embodiments 1, 2 and 3 have excellent ciprofloxacin catalytic degradation performance, as shown in the accompanying drawings 2, 3 and 4, after the reaction is carried out for 60 minutes, the removal rate of ciprofloxacin reaches more than 98%, and the comparative example (PDS single oxidation) is almost unchanged. Meanwhile, the used sample is subjected to X-ray diffraction analysis (figure 5), and the sample has obvious diffraction peaks at the positions of 10 degrees, 23 degrees, 33 degrees and 60 degrees, which indicates that the used sample still has the crystal phase structure of hydrotalcite-like compound.

Examples 4 and 5 active oxygen species identification experiments were performed. As shown in figure 6, the concentrations of benzoic acid, nitrobenzene and furfuryl alcohol did not change significantly during the reaction, indicating that the three organics were not degraded. Meanwhile, no obvious free radical signal was detected in electron paramagnetic resonance experiments (fig. 7 and 8). Therefore, hydroxyl radicals, sulfate radicals and singlet oxygen are not generated in the reaction system.

Example 6 evaluates the performance of persulfate intercalation hydrotalcite-like slow-release catalytic material in catalyzing and degrading various quinolone antibiotics (figure 9). The result shows that the synthesized material has obvious degradation effect on various quinolone antibiotics, and the removal rate of pollutants after the reaction for 60 minutes reaches more than 98%.

The invention provides a preparation method of an environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material, and raw materials used for preparation have the characteristics of convenience in material acquisition, low cost, environment friendliness and the like. The sample can inhibit the release of persulfate by-product sulfate radicals in the using process, the risk of secondary pollution is reduced, and the sample has excellent degradation performance on new quinolone antibiotic pollutants.

The above description is only an embodiment of the present invention, and the protection scope of the present invention is subject to the protection scope of the appended claims.

Claims

1. A preparation method of an environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material is characterized by comprising the following steps: uniformly mixing a divalent metal nitrate solution and a trivalent metal nitrate solution to be recorded as a solution A; taking the alkaline solution as a solution B; adding the solution A and the solution B into persulfate solution which is introduced with nitrogen at the same time under the room temperature environment, and keeping the pH value of the solution at 9-12; after the dropwise addition is finished, aging the reaction mixed solution for 10-20 hours in the nitrogen atmosphere; then centrifugally separating, washing the obtained sample to be neutral, and freeze-drying; the finally obtained solid sample is the environment-friendly persulfate intercalated hydrotalcite-like slow-release catalytic material;

wherein, the divalent metal salt in the divalent metal nitrate solution is a mixed solution of calcium nitrate and magnesium nitrate, and the weight ratio of calcium nitrate: the molar ratio of the magnesium nitrate is 0-1; the trivalent metal salt in the trivalent metal nitrate solution is a mixed solution of ferric nitrate and aluminum nitrate, wherein the ratio of ferric nitrate: the molar ratio of the aluminum nitrate is 0-1; divalent metal nitrate solution: the molar ratio of the trivalent metal nitrate solution is 2-4;

2. The use of the slow-release catalytic material prepared by the preparation method according to claim 1 in water treatment, characterized in that:

the prepared slow-release catalytic material is added into organic wastewater of 10 milligrams per liter of quinolone antibiotics, and under the stirring condition, after 120 minutes, the removal rate of the quinolone antibiotics in the water reaches more than 95 percent; the quinolone antibiotic is one of ciprofloxacin, ofloxacin, enrofloxacin and norfloxacin.